Re: Constraints and Functional Dependencies

Marshall wrote:
> On Feb 24, 6:41 am, paul c <toledobythe..._at_oohay.ac> wrote:> ...> Yeah. You'd need another constraint to express that, and I don't think> it would be possible to express the constraint that foreign keys must> reference primary keys, because that would be a second order> formula: it quantifies over formulas.> ...

If that's true, doesn't it mean that requiring the referenced attribute
to be key can't be a consequence of the strict RM which assumes FOL?